1. Field of the Invention
The invention relates in general to omni-positional hoist rings and other lifting fixtures, and, in particular, to hubs and nuts for the wrenchless mounting of omni-positional lifting fixtures to a substrate, and that are particularly suited for use under circumstances where lifting fixtures are to be mounted to trench plates.
2. Description of the Prior Art
Safety hoist rings of various that are capable of pivoting through an arc of 180 degrees and of swiveling through a full 360 degrees are well known and widely used. The shackles or U-bars in such devices are capable of moving so as to be aligned exactly with the direction of a tensile load applied from anywhere within a hemisphere that is disposed about the hoist ring assembly. Such safety hoist rings that comprise omni-positional lifting fixtures include, for example, Tsui et al. U.S. Pat No. 4,641,986 (a threaded central stud is surrounded by a flanged bushing that bears on the surface of a load, a collar that is slightly shorter than the bushing rotatably surrounds the cylindrical body of the bushing, the enlarged bulbous opposed ends of a U-bar or shackle are turned into opposed axial alignment with one another and are pivotally captured in cavities defined between the flange of the bushing and the collar); Tsui et al. U.S. Pat. No. 4,705,422 (a threaded central stud is surrounded by a flanged bushing that bears on the surface of a load, a collar that is slightly shorter than the cylindrical body of the bushing rotatably surrounds the cylindrical distal portion of the bushing, the opposed ends of a U-bar or shackle are pivotally pinned to the collar, and the axially aligned pins are held in the collar by clips on the radially inner ends thereof); Tsui U.S. Pat. No. 5,405,210 (a threaded central stud is surrounded by a flanged bushing that bears on the surface of a load, a collar that is slightly shorter than the cylindrical body of the bushing rotatably surrounds the cylindrical distal end of the bushing, the radially flattened enlarged opposed ends of a U-bar are turned into opposed axial alignment with one another and are pivotally captured between the collar and the flange of the bushing); Tsui et al. U.S. Pat. No. 5,848,815 (a threaded central stud is surrounded by a flanged bushing that bears on the surface of a load, a collar that is slightly shorter than the cylindrical body of the bushing rotatably surrounds the cylindrical body of the bushing, the opposed ends of a U-bar or shackle are pivotally pinned to the collar, and the axially aligned pins are held in the collar by retainer pins that are driven through the collar and into the radially inner ends of the pins); Tsui et al. U.S. Pat. No. 5,979,954 (a shackle is pivotally pinned to the distal end of a lift stud by means of a clevis pin, an externally threaded headed bushing is adapted to being threadably inserted into a bore in a load to bear against the surface of the load, the cylindrical proximal end of the lift stud is rotatably received in the bushing and retained there without binding with the bushing by a threaded cylindrical nut mounted to the proximal end of the lift stud that protrudes through the bushing, and the external diameter of the cylindrical nut is larger than the internal diameter of the bushing and smaller than the external diameter of the bushing so as to pass through the threaded bore in which the bushing is mounted, yet retain the proximal end of the lift stud within the bushing); Tsui et al. U.S. Pat. No. 6,022,164 (The enlarged distal end of a threaded stud defines a cavity that opens axially away from the stud, an enlarged proximal end of a hoist head is rotatably trapped in the cavity and the distal end of the hoist head is pivotally connected to a shackle through a clevis pin); and Alba U.S. Pat. No. 6,199,925 (a hoist ring in which very high tensile loads on the mounting shank are achieved by the use of a plurality of tensioning bolts).
Other hoist rings that comprise omni-positional lifting fixtures include, for example, Larson U.S. Pat. No. 3,905,633 (the trunions for mounting a U-bar are integral with a lift body that is rotatably mounted through a pair of hat shaped retainer plates to a threaded center stud); Andrews U.S. Pat. No. 4,431,352 (similar to Andrews U.S. Pat. No. 4,592,686 except that the bushing is frustoconical in shape); Andrews U.S. Pat. No. 4,592,686 (pivot axles for a U-bar are inserted into and pinned to a lift body that is rotatably mounted through a flanged bushing to a threaded center stud); Seidel U.S. Pat. No. 4,699,410 (a D-ring is pivotally trapped in a two-piece lifting body which is in turn rotatably trapped within a cavity in an external housing for rotation about a threaded center stud); Hansen II U.S. Pat. No. 5,052,869 (an omni-positional tie down structure, which is representative of lightly constructed tie down devices that are intended to be pre-assembled and mounted to the body of a carrier to provide an attachment point for cargo lashings); Mueller U.S. Pat. No. 5,286,130 (a lift body having a shackle pivotally pinned by a clevis pin to its distal end, and the cylindrical head of a screw rotatably trapped entirely within an axially facing cavity in the proximal end of the lift body, where a threaded port extends laterally through one side of the proximal end of the lift body into the cavity to enable the temporary locking of the lift body to the screw so that the screw can be tightened into a threaded bore in a load by rotating the lift body); Lecourt U.S. Pat. No. 5,580,110 (a lift body with axially opposed trunions is rotatably and permanently mounted about a threaded center stud, the opposed ends of a shackle are pivotally mounted on the trunions by means of an undisclosed procedure); Sawyer U.S. Pat. No. 5,586,801 (similar to Tsui et al. U.S. Pat. No. 4,705,422, except the center stud is welded to the load); Schron, Jr. et al. U.S. Pat. No. 5,634,734 (a D-ring is pivotally trapped in a two-piece lifting body, which is in turn rotatably mounted on a threaded center stud, and the lifting body is laterally pierced to allow access to rotatably tighten the threaded center stud); Martin U.S. Pat. No. 5,775,664 (the enlarged end of a mushroom shaped lift body is rotatably trapped in a cavity in a plate, the plate is bolted to a load, and a lifting ring is mounted in a cross-bore in the exposed end of the lift body); Morghen U.S. Pat. No. 5,823,588 (the enlarged circular head at the proximal end of a mushroom shaped lift swivel is rotatably trapped within a cavity in a mounting plate, the opposed ends of a shackle are pivotally mounted on a bolt that extends transversely through the distal end of the lift swivel, and the mounting plate is secured directly or indirectly to the load); Chandler U.S. Pat. No. 5,927,780 (is similar to Andrews U.S. Pat. No. 4,592,686 except that the shackle is generally H-shaped to accommodate attachment to a flat web); Kwon U.S. Pat. No. 6,039,500 (a side pull hoist ring wherein a shackle is mounted through a clevis pin to a lift body, the lift body is mounted for quick detachment to a load, but the hoist ring will not safely support loads applied from any direction, that is, this is not an omni-positional lifting fixture. Detachment is accomplished by lateral movement of the lift body, and a light elongated tongue member is employed to retain the lift body in the mounted configuration. The application of a substantial load parallel to the axis of the mounting screw would bend the elongated tongue and pull the lifting body away from the load.); Fuller et al. U.S. Pat. No. 6,068,310 (a D-ring is pivotally received in the throat of a clevis, and a center stud is rotatably received in the opposed ends of the clevis so that the pivot axis of the D-ring is offset from the rotational axis of the clevis); Pearl U.S. Pat. No. 6,161,883 (a hoist ring with a U-bar pivotally pinned to a lift body that is rotatably mounted to a flanged bushing, and with a large diameter skirt member coupled to a bi-threaded center stud that is threaded into a trench plate).
Typically, such previous omni-positional lifting fixtures comprised a shackle or U-bar that was pivotally connected to a rotationally mounted member such that the desired omni-positional pivoting and swiveling was achieved. The prior omni-positional lifting fixtures included a retainer that attached the fixture to a load so that some part of the fixture engaged with and bore firmly against the load. The retainer could be part of (see Tsui et al. U.S. Pat. No. 5,979,954) or separate from (see Tsui U.S. Pat. No. 5,405,210) the rotationally mounted member. Usually, but not always, (see Morghen U.S. Pat. No. 5,823,588, particularly FIG. 8, and Martin U.S. Pat. No. 5,775,664) the rotationally mounted member was mounted for rotation about the longitudinal axis of the retainer, that is, the rotationally mounted member generally rotated about the longitudinal axis of a screw or stud that was attached to the load. Usually, but not always, (see Fuller et al. U.S. Pat. No. 6,068,310) the pivotal axis intersected with the rotational axis. Often, but not always, (see Sawyer et al. U.S. Pat. No. 5,586,801) the retainer was threaded, and screwed into a mating threaded hole in the load. The shackle or U-bar was generally configured to accept the lifting member with which it was expected to be used (see, for example, Chandler U.S. Pat. No. 5,927,780, Tsui et al. U.S. Pat. No. 4,641,986, and Kwon US Des. 417,328).
Typically, omni-positional lifting fixtures are drawn very tightly against the substrate by the retainer so that the weight of the load that is lifted is distributed over the footprint of the lifting fixture on the substrate. Regardless of the mounting type, any misalignment between the lifting fixture and the substrate generally creates a substantial safety risk, because in such a circumstance the load is born primarily by the retainer rather than the portion of the fixture that bears against the substrate. It requires a certain amount of skill and equipment to drill and, if necessary, tap a hole so that it is square with the surface of the substrate. Such skill and equipment are not always available at the site where a safety hoist ring is to be attached to a load, particularly in the construction arts. Also, in many circumstances the reverse side of the load is not accessible, so a fastening element can not be applied to the retainer on the reverse side of the load.
Trench plates, vault covers, and the like, are widely used at construction sites to temporarily cover open excavations, and in completed underground construction projects. Trench plates, and the like, are typically large flat steel plates that weigh upwards of 5,000 to 10,000 pounds each. The handling of plates presents many difficulties. Safety is a serious consideration in handling these very heavy plates. Such plates are typically attached to a lifting device, such as a crane, through some suitable coupling. Various expedients have been proposed for such couplings. See, for example, Rogers U.S. Pat. No. 5,713,695 (a square insert for welding into an opening in an excavation cover plate, which insert includes two laterally extending pins for securing the opposed ends of a length of chain to the insert); Harter U.S. Pat. No. 4,974,992 (a excavation cover plate with a lift opening, and a pivotally mounted bail positioned in that lift opening); Silva, U.S. Pat. No. 4,304,432 (a lifting device for use with excavation cover plates wherein the lifting device is releasably locked into a specially configured lifting hole in the plate); and Pearl U.S. Pat. No. 6,161,883 (a hoist ring with a large diameter skirt member coupled to a bi-threaded center stud that is threaded into the trench plate). Inserts for trench plates, which inserts have been precisely bored and tapped to mount lifting devices, have been used in the construction trades for years, particularly by the Department of Water and Power for the City of Los Angeles. Lifting plates with slots configured to allow a chain to pass in one position and not in another have been employed in the lifting arts. See, for example, Kilbert et al. U.S. Pat. No. 4,941,698.
Trench plates are often employed at construction sites where wrenches are not readily available. Pry bars, short lengths of reinforcing bar, and hammers are generally available on such construction sites. Such construction sites pose special challenges to the use of hoist rings and other lifting devices, and particularly to the mounting of such devices on trench plates. The safe usage of hoist rings and other lifting devices requires that they be securely mounted to the load that is to be lifted. This generally means that they are attached to the load by a threaded mount, which is torqued to some large predetermined value. Such torquing generally requires the use of wrenches. Where wrenches are not available workers may attempt to use other expedients, which results in an unsafe installation if the threaded mount is not adequately torqued down. Some torquing means is needed to enable the hoist rings to be safely mounted to a load or other substrate when wrenches are not available. Typically, lifting fixtures are attached to trench plates at the construction site for handling purposes during installation. They are then removed. When the construction is completed, the lifting fixtures are reinstalled and used to remove the trench plates. The lifting fixtures are usually removed again when the trench plates are in storage.
Bar knobs have long been used in the tooling industry. A bar knob is a threaded nut that has spaced apart projections extending generally parallel to the axis of the threaded bore so that a bar can be inserted between them, in a direction generally normal to the axis of the bore, and torque applied. A bar knob generally resembles a castle nut where the axially projecting lugs are widely spaced from one another to receive a pry bar therebetween.
Pearl U.S. Pat. No. 6,161,883 discloses an enlarged star shaped plate mounted on a threaded hoist ring mounting stud. Hammering on the radially extending arms of the star tightens or loosens the threaded mounting stud. The arms rest on the surface of the load.
These and other difficulties of the prior art have been overcome according to the present invention.